DC861 QUICK START GUIDE
3
Figure 4. DC861A Inputs, Outputs, Jumpers, Sw itches and Connectors.
PG A A Input
PG A B Input
PG A A O utput
PG A B O utput
Jumper J6
. Sets the LTC6912 for a dual or a single power supply operation.
In a single supply operation, the AG ND pin of the LTC6912 is connected to V+/2 thru the
J6 jumper and the V- input must be grounded externally. In addition, in a single supply
operation the PGA A and B input should have a D C bias equal to V+/2 or be AC coupled.
Jumper J2:
Sets the LTC6912 for a dual PGA or a 2:1
analog M UX operation (the D1 LED is in a 2:1 M UX).
SW 1 to D -O n:
Provides
power to the digital circuits
and 4-digit LED.
SW 1 to D -O ff:
Turns off
power to the digital circuits
and 4-digit LED.
SELECT SW
: Selects 1 of 4 digits
(the selected digit is blinking).
Pressing the SELECT SW for more than three seconds changes the
LED display to show the LTC6912 setting in decimal.
U P SW :
Increments selected digit.
D O W N SW
: Decrements selected digit.
SEN D SW :
Sends SPI control to the LTC6912.
STO R E SW :
Stores last SPI control setting (available on power-up).
the 4-digit LED display
shows the LTC6912 gain
setting in hex. The display
switches to decimal if the
SELECT sw is pressed for
more than three seconds.
Pow er
Supply
Inputs.
SW 2 to O FF:
Sets the board for
stand-alone or slave operation.
SW 2 to O N :
Sets the board as mas-
ter SPI controller in a two DC861
board connection (the D2 LED is on
in daisy chain master operation).
Jumper J4.
Flat ribbon cable
connection to a
DC861 SPI master in
daisy chain operation.
Jumper J3.
Flat ribbon cable connection
to a DC861 SPI slave in
daisy chain operation.
SW 3 to ENBL:
Power is on for the
LTC6912.
SW 3 to SHD N :
Sets the LTC6912 to a hard-
ware shut down (D4 LED is
on in SHDN).
For normal board operation,
set SW 3 to EN BL.